Automatic choke control for internal combustion engines



May l, 1934- i y A. c. PURPURA 1,957,289

NUTONATIG cEoNE coNTRoE Fon INTERNAL comEUsTIoN ENGINES jiledpem 5. l19:51 2 sheets-sheet 1 May l; 1934- A. c. PURPURA y 1,957,289-

AUTONATIOCHOKE CONTROL FOR INTERNAL OOMBus'rIoN ENGINES Patented May 1,1934

UNITED STATES "PATENT er1-ICE AUTOMATIC CHOIE CONTROL FOR IN- TERNAL COMBUSTION ENGINES August C. Purpura, Chicago, Ill. Application December 5, 1931, serial No. 579,144'

20. claims. (o1. y12a-119) This application is a continuation in part of application #542,089, led' byme June 4, 1931 on an Automatic choke control for' automobile engines.

My invention relates to means forautomatically modifylng the mixture of air and fuel supplied to an internal combustion engine, so as to secure an efficient mixture and to expedite the starting and speeding up of the engine regardless of the temperature of the engine and of the outer temperature has risen to a predetermined extent.

Moreover, ry invention aims to provide control means for these purposes which also will increase the supply of fuel to the'engine both during the starting of the engine when the latter is cold and during the warming-up period, and which lwill' automatically discontinue this increase of -the fuel supply.

In an additional aspect, my invention aims to provide an auxiliary control mechanism for the above recited purposes which can readily be attached as a unit to customary types of internal combustion engines, and particularly to those ,.,commonly employed on automobiles, without re- "'quiring any extensive drilling or machinery.

In this aspect, my invention aims to provide a mechanism of the above recited characteristics which will-automatically increase theidling adjustment of the fuel throttle of an automobile when the engine is cold, so as to prevent a stalling of the vehicle in cold weather; which will eliminate res due to a spitting of name through a carbureter, and which also will prevent excessive gasoline consumption and excessive oil dilution v'by entirely eliminatingA the use of a hand-controlled choke.

. In addition to affording these highly desirable 4 characteristics in its construction and functioning, my invention also aims to provide an automatic control mechanisml of the above recited class, wh'ch will be independent of the usual starting switch and which will not necessarily require any supply of electric current; thereby permitting my choke control to be used to equal air, and without requiring any skill on the part advantage on magneto-equipped and handcranked auto trucks, and also preventing any drain on the more customary battery of a car equipped with an electric starter at the very time when the full capacity of the battery may be required for operating the starter. Furthermore, .my invention aims to provide an auxiliary air and fuel supply control mechanism for the above recited purposes which will be low in cost of manufacture and which can readily be attached as a unit to customary types of internal combustion engines, and particularly to the types commonly employed on automobiles, without requiring any extensive drilling or machining.

Still further and also more detailed obects of my invention will appear from the following specification and from the accompanying drawings, in which drawings Fig. 1 is an elevation of an embodiment of my invention connected to a carbureter, air inlet and manifold inlet, showing the mechanism as it appears after the engine has been started and before the engine has warmed up.

Fig. 2 is an enlarged and fragmentary horizontal section, taken along the line 2-2 of Fig. 1 80 with the leg portions of the suction-cylindersupporting base omitted.

Eig. 3 is a view similar to a portion of Fig. 1, showing the position of different portions of the mechanism when the engine has warmed suiiciently for reducing the suction in the largerI control cylinder.

Fig. 4 is a view of the same parts taken when the engine is running at normal warmth.

In the embodiment of the drawings, the ow of air through the intake pipe 1 of Fig. 1 is con- 0 trolled by a damper 2 fastened to the shaft 3 of a rocking lever 4. This lever has one of its oppositely directed arms connected respectively by a link 5 to the rod 6 on a piston 7 which slides in a cylinder 8; while the other lever arm is con- 95 nected by a second link 9 to the rod 10 on a second piston 1l. This second piston 11 is slidable in a cylinder 12 which is considerably larger in bore thanthe cylinder 8;' and the link 9 associated 100 with the said second piston vhas a longitudinal slot 13 through which a pin 14 on the lever extends, whereby this slot permits a limited lost motion between the lever or rocking arm 4 and the larger diametered piston 11. The outer end of the smallerf-diametered cylinder 8 is connected to the manifold 31 by a. suction pipe 15 which maintains a continuously open connection to that cylinder, so that the smaller diametered piston 7 is always subject to the sucno tion in the manifold when the engine is running. The manifold is also connected to the outer end of the larger-diametered cylinder through a suction pipe 16, but the suction through this type is automatically controlled according to the temperature of the manifold. Y

For this control purpose I am here showing a tapered valve member 17 mounted on one endof a bimetallic strip 18 disposed within the manifold and fastened at its lother end to the latter; the arrangement of the two metals being such that this strip will be flexed away from the inlet of the suction pipe 16 when cold (so as to open the inlet of the latter pipe as in Fig. l), but will be flexedtoward the said inlet when the intake pipe is heated, so as to close the inlet of the suction pipe 16 as in Fig. 3.

Both of the piston rods 6 and 10 slide through 4a base member 20 seated upon and fastened to the exterior of the intake pipe l so that portions of this member serve as the inner heads of the two. cylinders. Interposed between this base member and the rocking lever 4 is a spiral tension spring 21 which is disposed so that the axis of the spring will pass across the axis of the lever shaft 3A when the lever moves from the cold starting position of Fig. 1 to the normal running position of Fig. 3, and vice versa.

Extending into the larger diametered cylinder 12 through the outward end 12A of the-latter is' a stop screw 22 which desirably extends axially of the cylinder and is disposed for engaging the larger piston 11 to limit the outward (or valveopening) movement of that piston. This stop screw is connected to a stationary member, such as a riser screw 23 on the piston head 12A by a coded bimetallic strip-24 which has its two metal portions disposed so that the screw will be rotated for advancing it`into the cylinder l2 when the said coiled strip warms up, and for moving the tip of the screw farther from the base member 19 when the coiled strip cools. Thus arranged, this bimetallic coil automatically moves the stop screw 22 in response to the temperature around the said coil exteriorly of the cylinders, and hence according to the temperature of the air under the hood of an automobile when my control mechanism is used in connection with an automobile engine, so as to vary the extent to which the slot 13 in the link 9 will permit lost motion between the valve and the larger diametered piston l1.

With the mechanism thus-arranged, lthe uninterrupted suction through the suction pipe 1.5 during the running of the engine continuously tends to lift the smaller piston 8; and when the manifold 3l is hot so that the valve member 17 shuts oil the suction in the larger diametered cylinder 12, this lifting action on the smaller piston 7 holds the parts as shown in Fig. 4. In this position, the larger piston l1 is halted by the engagement of a pin 6A on the piston rod with the base member 19; the lever pin 14 is at the outer endof the slot 13 in the link 9; and the spring 2l assists the smaller piston in holding the valve 2 open so as to permit the maximum flow of air through the pipe air-inlet l, which pipe may be one of a plurality of intakes for the associated carbureter, according to .a common custom. If the engine is then stopped,` the suction through the suction pipe 15 ceases, but the throwover spring 21 will continue to hold the air valve 2 in its full open position as shown in Fig. 4; and if the engine is restarted while the 'intake is still sufficiently hot for keeping the suction-controlling valve 17 on its closure position, my mechanism will not be actuated in any manner during this starting. V

However, if the engine has cooled sufliciently while idle, so that the thermostatic'suction-controlling valve 17 has opened, a starting of the engine will initially create a suction in both cylinders, with the following effect: Owing to the difference in diameters of the two pistons, these will exert oppositely directed and unequal pulls on the rocking lever 4; and with the spring 21 of a tension exerting less elfort on the lever than the difference between the pulls of the two pistons, the lifting action on the larger diametered piston 10 overpowers the combined action of the smaller piston 7 and the spring. Consequently, the starting of the engine 'will rock the lever 4 (in a counterclockwise direction from the running position of Fig. 4) to the position of Figs. 3 and 4, in which the larger-diametered piston 11 is halted by engaging the stop screw 22.

In other words, the differential suction action acts through the two links 5 and 6 to rock the lever until the throw-over spring 2l snaps past the axis of the levershaft 3 and the larger piston is halted by the stop screw 22 (or to a position in which the intake is only partly closed); and the pull of the spring 21 then completes the closing of the valve by a further movement (to the position shown in Fig. 1), this additional movement of the lever in the valve-closing direction being permitted by the slot 13 in the link 9. Since the outward movement of the larger piston is limited by the thermostatically controlled stop screw 22, the extent of this additional movement of the valve is varied according to the temperature around the mechanism, so that the valve will be closed to a less extent during the initial action of my mechanism at the starting of the engine during cold weather than at warm prevailing temperatures.

The rocking lever 4 which moves lthe air-control valve 2 is desirably also connected to the usual fuel valve 26, as for example by a connection to the usual valve-operating lever 27 which is actuated by the throttle rod 37. Forthis purpose I am showing a link 48 pivoted at one end to the rocking lever and having in its other end a lonl gitudinal slot 28 in which a pin 29 on the valve lever 27 is slidable. This slot is of such length and position that its ends are out of engagement with the pin 29 during the operation of my mechanism whenever the throttle rod 37 is in its normal inoperative position, as shown in the drawings. However, if this rod is slid forward (by its usual manual operation from the dashboard of the car) so as to open the fuel valve 26 during the starting of the car, the pin 29 will engage the forward end of the slot inthe link 28 so as to move this link forwardly and downwardly, thereby correspondingly opening the air valve 2 also.

Thus arranged, this connection to the fuel` valve of the carbureter causes the supply of fuel to be increased automatically whenever the major piston 11 is initially drawn up against the stop screw 22. Then, if the engine spits during of the mixture which caused the spitting. And

since the just described effect of the so-called spitting momentarily (closes the air control Valve 2, the back firing cannot cause flames to issue. through the air inlet, so that my mechanism automatically prevents the res due to this cause.

` assists the uninterrupted suction on the smaller piston in tending to rock the lever 4 (against the resistance of the spring 21) for opening the air valve. As soon as the suction in the smaller cylinder 8 becomes sufficient for this purpose, the piston 7 rises and snaps the spring 21 past the axis of the valve and lever shaft 3, whereupon the spring cooperates with this piston in raising the latter to the position shown in Fig. 1, in which position the valvep2 is fully open and the fuelvalve opening thrust of the rod 26 is relaxed.

When the engine is then stopped, the suction in the smaller cylinder 8 is discontinued, but the spring 21 continues to hold the.air valve open, so that my choke mechanism is inoperative if the engine is again started while the intake manifold is still warm. However, if the engine has cooled before it is restarted, the thermostatically controlled valve member 17 will open the suction duct to the larger cylinder, so that my mechanism will again operate according to the previously described cycle. v

Since a starting of the engine always produces an intake suction, my mechanism is obviously independent of the means employed for the starting. Consequently, its operativeness is not affected by the condition of any battery or starting mechanism, and requires no electrical connections. Moreover, entire operation is entirely automatic, thereby eliminating the need of a hand-operated choke control which so often leads to a flooding of the carbureter. This automatic action even' includes the adjustment for exterior temperature conditions, and also includes an automatic opening of the fuel valve to a wider extent than that afforded by the adjustment of the carbureter, thereby modifying the so-called idling adjustment so as to prevent a car equipped with my control mechanism from stalling in tranc, during the warming up period;

However, while I have heretofore/ described an embodiment of my invention which includes both the auxiliary fuel-supply control and a temperature-responsive stop adjustment for regulating the extent to which the air-intake valve is closed, I do not wish to be limited to the conjoint use of these auxiliary features. Both of these might be omitted but are desirably employed also,` because the stop adjustment (when suitably proportioned) makes my control substantially independent of thev prevailing weather conditions in its responsiveness; and because the auxiliary fuel valve-control insures the temporary increasing changes might be made Without departing either from the spirit of my invention or from the appended claims.

,'For example, instead of making Vthe two suction cylinders and their pistons of relatively different diameters and connecting themv to lever arms of `equal length, I may make the cylinders equalv in-diameter and connect them to oppositelydirected lever arms of unequal length, as shown in Fig. 3. In this ca'se, the effective ,pull on each piston will be the sa'me when the suction ducts to both cylinders are open, but the thrust exerted by the piston in the cylinder 12A will have a greater effect on the rocking lever 4A than that in the vcontinuously suction-connected companion cylinder. In either case, the intake valve is connected to two oppositely acting suction means, the more powerfully effective of these means has its suction controlled in response to the temperature of the intake manifold.

`Since the temperature of this pipe varies with that of the engine, the control of the suction in the effectively weaker suction-actuated means is responsive to variations in the temperature of the engine. Hence itwill also be obvious that the position of the temperature-responsive element 18 and of the valve controlled by it may be varied, so long as the vsaid element is influenced by changes in the temperature of the engine.

Moreover, the operation of my control mechanism will obviously be the same regardless of the purpose served by the engine or the like to which my mechanism is applied, so that my invention will be equally applicable for use in connection with engine driven pumps, hoists or other devices. Hence I do not wish to be limited as to the nature -of the device on which my invention is employed, although it is particularly suitable for use on automobiles.

In the illustrated embodiment, I have shown the two suction cylinders as mounted on a base plate 29 which seats upon and is fastened to the air intake pipe 19 between the air lter 41 (at the inlet end of the air intake) and the mixing chamber 42 to which both the float chamber 43 and the'air intake are connected. In Fig. 1 I have also pictured the suction-controlling thermostatic member 18 and the adjacent end of the suction pipe- 16 as fastened to a gasket 44 which is clamped between the usually adjacent flanges on the carbureter and the intake 3l of the manifold, thus showing how easily my invention may` be adapted for use Without changes in any part words closing and closure are used in a relacontrols the air intake may be formed so that it merely throttles that intake when the engine has only a single air intake, or may-be formed so as to close the intake entirely when the engine also hasan additional air intake. I claim as my invention:

l. An air intake control mechanism for an internal combustion engine having an air intake duct, comprising: a movable valve member controlling thesaid duct; of intake-closing means responsive to the running of the engine for moving the said member toward its closure position; separate and relatively weakenmeans responsive to the suction of the engine, for urging'the said member away "from its. closure position; and means responsive to the temperature of the engine for annulling the Aoperation of the intaketive sense, since the movable valve member which closing means when the said temperature is above a predetermined minimum.'

2. An lair intake control mechanism as per claim 1, including spring means tending to hold the valve member in its closure position after the valve member has been moved to a certain extent toward that position by the intake-closing means.

3. An air intake control mechanism as perl claim 1, including spring means tending to hold the valve member in its closure position after the valve has been moved to a certain extent toward that position by the intake-closing means,` the intake-closing means peing operatively stronger than the spring means.

4. An air intake control mechanism as per claim 1, including spring means tending to hold the valve member in its closure position after that member has been moved to a certain extent toward that position by the intake-closing means, the spring means being so disposed that it also cooperates with .the said stronger means for tending to hold the said member in its valveopening position when the operation of the intake-opening means has been annulled by the last named means.

5. An air intake control mechanism as per claim 1, including a lost-motion connection-between the said valve-member and the intakeclosing means.

6. An air intake control mechanismv as per claim 1, including auxiliary temperature-responsive means for varying the extent to which. the valve member is movable towards closure position.

7. An air intake control mechanism for an internal combustion engine having an air intake duct, comprising: a movable valve member controlling the said duct; intake-closing means operative when the engine temperature is below a predetermined minimum, for moving the said member part way toward its closure position when the engine is started; spring means moving the valve member further in the intake-closing direction after the valve member has been moved part way by the intake-closing means, and suction-actuated means responsive to the intake suction of the engine and connected to the said member so that the said suction tends to move the valve member in the intake-opening direction; the spring means being of insuiiicient strength for alone resisting the intake-closing means when the said suction-actuated means are inoperative.

8. An air intake control mechanism as per claim 7, in which the spring means are arranged for resisting the movement of the Avalve member away from its closure position during only apart of the permitted movement of the said member.

9. An air intake control mechanism'for an internal combustion engine having an air 'intake duct, comprising: a movable valve member controlling the said duct; valve-closing means responsive to the running of the engine for moving the said member part way toward its closure position; movement-completing means, operating after the said member has been moved to a predetermined extent in the said direction by the valve-closing means, vfor completing theI movement of the said member in that direction; valve-opening means responsive .to the suction of the engine, for urging the said member away from its closure position; and means responsive to the temperature of the engine for annulling the operation of the valve-closing means when the said temperature is above a predetermined minimum.

10. In an internal combustion engine, a carbureter having an air intake duct, a movable valve member `controlling the said duct; two valve-operating means of relatively different vstrength both responsive to the suction in the manifold of the engine; oppositely acting connections between the valve member and the said means, the connections being so arranged that the stronger means tend to close the valve and the weaker means tend to open the valve; and means associated with the stronger means for annulling the suction thereon under predeter` mined operating conditions of the engine.

11. In an internal combustion engine, a manifold, a carbureter connected to the manifold and having an air intake duct; a movable valve membercontrolling the s'aidduct; two valve-operating means of relatively diierent strength both responsive to the suction in the manifold of the engine; oppositely acting connections between the valve member and the said two means, `the connections being so arranged that the stronger means tend to close the air intake and the weaker means tend to open the air intake; and means associated with the stronger means for annulling the suction thereonwhen the temperature vof the engine exceeds a predetermined minimum.

12. An airintake control mechanism for an internal combustion engine, as per claim 11, including temperature-responsive means for automatically varying the extent to whichv the said valve member can be moved by the said strongei` means.

13. An air intake control mechanism for an internal combustion engine, as per claim 11, including temperature-responsive means for automatically varying the extent to which the said valve member can be moved by the said'stronger means, the temperature-responsive means including a thermostatic member disposed exteriorly of the engine. K

14. An air intake control mechanism as per claim 10, includingy a throw-over spring operatively connected to the valve member for assisting either the stronger or the weaker of the said means according as the valve is opened respectively more or less than to a predetermined extent.

15. The combination with the air intake duct and the manifold of an internal combustion engine, of a movable valve member controllingthe said duct, two diierently diametered cylinders each connected at one end to the manifold, a piston slidable in each cylinder, a rocking lever fast with respect to the valve and having oppositely directed arms respectively connected to the two pistons; and a thermostatic valve associated with the connection of the larger diametered cylinder to the manifold for controlling the said connection so as to discontinue that connection 1after a. predetermined rise-in temperature, and so as to restore that connection when the temperature falls below a predetermined minimum.

16. An air intake control mechanism as per claim 15, including a link interposed between the larger diametered piston and the rocking lever, the link having a slot aiording a lost motion connection between the lever and the larger diametered piston.

17. In an internal combustion engine having an air intake and a manifold, an automatic control mechanism including a movable valve member controlling the said intake; two cylinders connected to the manifold; two pistons of relatively 4different diameter slidable respectively inthe ber in its closure direction, and whereby the suc- 1 tion on the smaller piston tendsfto move the said member in its intake-opening l`direction; and means responsive to a rise in the temperature of the engine beyond the said maximum for discontinuing the suction through the cylinder associated with the larger piston. A A

18. In an internal combustion engine, a control mechanism as per claim 17, in which the connections include a.rocking leverfa-st on the movable valve member and having oppositely directed arms respectively connected to the two pistons; and a throw-over spring connected to the lever and assisting either one of the pistons according to whether the valve is opened more or less than a predetermined extent.

19. In an internal combustion engine, a control mechanism as per claim 17, in which the connections include a rocking lever fast on the air valve member and having oppositely directed arms respectively connected to the two pistons; and a throw-over spring connected to the lever and assisting either one of the pistons according to .whether the valve is opened more or less than a predetermined extent; the connection between the lever and the larger diametered piston being arranged to aiord lost motion for permitting the spring to move the valve member, in the direction in which that member is moved by the larger piston, toa greater extent than to which the larger diametered piston moves the said member. n

20.'A control mechanism as per claim 17, including a stop member mounted on the\larger diametered cylinder for limiting the extent toy which the piston in that cylinder can be moved by suction, and temperature-responsive means for varying thevetlective position of the stop member` AUGUST C. PURPURA.

iss 

